Abstract: Disclosed is a composition, in particular a dispersion, which contains nanofiber material in at least one organic matrix component, said nanofiber material being pre-treated in at least one method step for adjusting the physical properties of the composition.

Abstract: A process for manufacturing high density boron carbide by pressureless sintering, enabling to create sintered products of complex shapes and high strength. The process comprises mixing raw boron carbide powder with carbon precursor, such as a polysaccharide, compacting the mixture to create an object of the desired shape, and finally carbonizing and sintering the object at higher temperatures.

Abstract: The production of ultrafine metal carbide powders from solid metal carbide and nitrogen-containing material is disclosed. The starting materials are fed together or separately to a plasma system where the solid metal carbide is melted and/or vaporized in the presence of nitrogen to form ultrafine metal carbide particles of high purity.

Abstract: A plurality of carbide, such as silicon carbide, tungsten carbide, etc., nanofibrils predominantly having diameters substantially less than about 100 nm and a method for making such carbide nanofibrils.

Abstract: The production of ultrafine metal carbide powders from polymeric powder and metallic precursor powder starting materials is disclosed. In certain embodiments, the polymeric powder may comprise polypropylene, polyethylene, polystyrene, polyester, polybutylene, nylon, polymethylpentene and the like. The metal precursor powder may comprise pure metals, metal alloys, intermetallics and/or metal-containing compounds such as metal oxides and nitrides. In one embodiment, the metal precursor powder comprises a silicon-containing material, and the ultrafine powders comprise SiC. The polymeric and metal precursor powders are fed together or separately to a plasma system where the feed materials react to form metal carbides in the form of ultrafine particles.

Abstract: A composite material includes an SiC porous ceramic sintered body, which is formed by preliminarily sintering a porous body, having a coefficient of thermal expansion lower than the coefficient of thermal expansion of copper to construct a network therein. A copper alloy impregnating the porous ceramic sintered body includes copper and one or more additive elements which are prepared to impart a coefficient of thermal conductivity of 160 W/mK or higher to the composite material. The additive elements include up to 5% of at least one element selected from Be, Al, Si, Mg, Ti, Ni, Bi, Te, Zn, Pb, Sn, and mish metal, and also contain unavoidable impurities and gas components.

Abstract: The present invention includes carbon synthesis devices and systems. The invention also includes machines and instruments using those aspects of the invention. The present invention also includes methods of carbon synthesis. The present invention includes an array of carbon nanotubes, each nanotube having a longitudinal axis. The nanotubes are placed into an array such that the longitudinal axes of all nanotubes in the array are substantially parallel. The array may be a two-dimensional array or a three-dimensional array. The present invention also includes methods of preparing such carbon molecular clusters and arrays thereof.

Abstract: A method for the manufacture of a structure from a carbide of a group IIa, group IIIa, group IVa, group IVb, group Vb, group VIb, group VIIb or group VIIIb carbon reactive element including the steps of: mixing the element with the carbon; and heating the carbon and the element to melt the element so that it reacts with the carbon to form the carbide; wherein, the carbon and element are heated by means of electromagnetic radiation having a frequency below the infrared spectrum. The method does not waste energy by unnecessary heating of the furnace or surrounding mold. The mold itself may be more stable because it is only heated by hot contained material and not by other sources of heat. Resulting formed products are not a sintered product and may approach one hundred percent of theoretical density. The carbon may be in the form of a powder that is mixed with the element or may be a porous carbon structure such as a graphite fiber mat or sheet into which the carbon reactive element is melted.

Abstract: A method for making a boron carbide containing ceramic involves pyrolyzing a precursor having one or more monosubstituted decaboranyl groups and at least one substituting group containing carbon. The precursor may be molecular, for example comprising two decaboranyl groups linked by a single substituting group, or polymeric, in which case the decaboranyl groups are part of the pendant group of the polymer while a portion of the substituting group makes up the polymer backbone. In either case, the substituting group may be a hydrocarbon, in which case boron carbide may be formed. Alternatively, the substituting group may contain carbon and another ceramic forming element (i.e., other than boron or carbon), such as silicon, nitrogen, or phosphorous, in which case a composite including boron carbide is formed.

Abstract: A method for preparing a carbon-containing composition is disclosed which comprises the steps of introducing, into a hot gas, a dispersion obtained by dispersing, in a decomposable carbon compound, a metal oxide and/or a metal compound which can be converted into the metal oxide by heating, to form a carbon-containing composition containing simple carbon and the corresponding metal oxide; and then collecting the formed carbon-containing composition. This carbon-containing composition is useful for the manufacture of a ceramic powder for sintering.

Abstract: In one aspect, the invention includes a method of forming a material containing carbon and boron, comprising: a) providing a substrate within a chemical vapor deposition chamber; b) flowing a carbon and boron precursor into the chamber, the precursor being a compound that comprises both carbon and boron; and c) utilizing the precursor to chemical vapor deposit a material onto the substrate, the material comprising carbon and boron. In another aspect, the invention includes a method of forming a catalyst, comprising: a) providing a substrate within a chemical vapor deposition chamber; b) flowing a carbon and boron precursor into the chamber, the precursor being a compound that comprises both carbon and boron; c) utilizing the precursor to chemical vapor deposit a first material onto the substrate, the first material comprising carbon and boron; and d) coating the first material with a catalytic material.

Abstract: The invention provides crystalline nanoscale particles and tubes made from a variety of stoichiometries of BxCyNz where x, y, and z indicate a relative amount of each element compared to the others and where no more than one of x, y, or z are zero for a single stoichiometry. The nanotubes and nanoparticles are useful as miniature electronic components, such as wires, coils, schotky barriers, diodes, etc. The nanotubes and nanoparticles are also useful as coating that will protect an item from detection by electromagnetic monitoring techniques like radar. The nanotubes and nanoparticles are additionally useful for their mechanical properties, being comparable in strength and stiffness to the best graphite fibers or carbon nanotubes. The inventive nanoparticles are useful in lubricants and composites.

Abstract: This invention relates to a process for forming metal or non-metal carbide fiber from the corresponding metal or non-metal containing material such as a silicon sol or mixtures thereof and silicon, silicon carbide or silicon oxide, or mixtures of silicon carbide and silicon or silicon oxide.

Abstract: The disclosure teaches a method for obtaining porous solids of refractory carbide with a large specific surface area. An exclusively organic, polymeric and/or copolymerizable compound, for example a resin, which can be coked and to provide a solid carbon skeleton, is mixed with a powder of metal, or metalloid, or a compound thereof which can be reduced by carbon. The mixture is shaped, the organic compound is cross-linked or hardened, and the compound is heat treated from 500.degree. to 1000.degree. C. to coke it, then heat treated to carburize it.

Abstract: Described herein is a method and apparatus for continuously growing single crystal whiskers of silicon carbide, silicon nitride, boron carbide and boron nitride by the VLS process under controlled reaction conditions. A growth substrate such as a plate of solid graphite is coated with a suitable VLS catalyst and is conveyed through a tubular furnace, into which is separately introduced two feed gases. The first feed gas contains a cationic suboxide precursor such as silicon monoxide or boron monoxide. The second feed gas contains an anionic precursor compound such as methane or ammonia. The precursor compounds react upon exposure to the catalyst by the VLS process to produce crystalline whiskers. The associated apparatus includes a conveyor assembly that continuously circulates multiple substrate growth plates through the furnace and past a harvesting device which brushes the whiskers from the plates and removes them by vacuum collection. Whiskers of uniform size, shape, and purity are produced.

Abstract: A method and apparatus are provided for producing a product comprising a carbide compound, such as for example silicon carbide. A reactor is provided which has a chamber defined therein which is divided into a combustion zone and a reaction zone. A combustible mixture is injected into the combustion zone in a direction generally toward the reaction zone, and is accordingly combusted in the combustion zone. At least one reactant (i.e. silane) is injected at the boundary between the zones into the reactor chamber in a direction generally parallel to the longitudinal axis of the chamber so as to react to form raw product comprising the carbide compound.

Abstract: A method of imaging a corporeal situs by radiological techniques, comprising delivery to the corporeal situs of an imagingly effectively amount of a physiologically acceptable composition comprising a boron reagent. A variety of illustrative boron reagents is described, including iodinated boron salts, and boron-containing cyclophosphazene and polyphosphazene reagents having radiopaque character. The reagents and method of the present invention may be employed for a wide variety of radiological imaging applications, e.g., excretory urography, angiocardiography, and aortography.

Abstract: A powdered admixture of a boron, carbon, nitrogen or silicon derivative of a first metal is combined with a source of a second metal and, optionally, a source of a third metal or an iron-group metal, subjected to densification conditions (heat and pressure), partially reacted and converted to a hard, wear resistant material. The wear resistant material contains an amount of the first metal derivative as well as a material of varying stoichiometry which is the partial reaction product of components of the powdered admixture The material may also contain residual, unreacted portions of components other than the first metal derivative. Articles formed from this material can be useful as, for example, nozzles in abrasive or nonabrasive waterjet cutting machines and various parts of wire drawing apparatus.

Abstract: An apparatus is provided for producing a product comprising a carbide compound, such as for example silicon carbide. A reactor is provided which has a chamber defined therein which is divided into a combustion zone and a reaction zone. A combustible mixture is injected into the combustion zone in a direction generally toward the reaction zone, and is accordingly combusted in the combustion zone. At least one reactant (i.e. silane) is injected at the boundary between the zones into the reactor chamber in a direction generally parallel to the longitudinal axis of the chamber so as to react to form raw product containing the carbide compound.

Abstract: Uniform, fine ceramic powder is prepared using an apparatus comprising (a) a cooled reactant transport member; (b) a reactor chamber; (c) a heating means; and (d) a cooling chamber. The reactant transport member comprises a wall defining a conduit that communicates with the reactor chamber, with a gas-flow space being defined along the perimeter of the transport member and in communication with the reactor chamber. The reactor chamber comprises a wall defining a reaction zone, and the heating means is associated with the reaction zone, and adapted for heating reactants in the reaction zone. The cooling chamber comprises a wall defining a cooling zone that communicates with the reactor chamber. In one embodiment the communication is by means of a cooling inlet, the diameter of the cooling zone being larger than the diameter of the cooling inlet. The temperatures of the reactant transport member, the reactor chamber, and the cooling chamber are independently controllable.

Abstract: A process for producing fibres composed of or coated with carbides or nitrides. The process involves forming a first reaction zone containing microfine particles of an oxide (or oxide precursor) of silicon or a suitable metal (e.g. boron) uniformly mixed with carbon (or a carbon precursor); forming a second reaction zone comprising a layer having a thickness of 1 cm or less of a porous mass having a density of 1 g/cc or less formed of short or continuous fibres made of or coated with carbon (or carbon precursor); heating the first reaction zone in a non-oxidizing atmosphere to generate a gaseous sub-oxide of the silicon or metal; simultaneously heating the second reaction zone so that the gaseous sub-oxide diffuses into it and reacts with the carbon to form carbide or nitride on the fibres; and separating the resulting fibres from any carbide or nitride whiskers that may have formed in the second rection zone. Short or continuous fibres (e.g.

Abstract: Uniform, fine ceramic powder is prepared using an apparatus comprising (a) a cooled reactant transport member; (b) a reactor chamber; (c) a heating element; and (d) a cooling chamber. The reactant transport member comprises a wall defining a conduit that communicates with the reactor chamber, with a gas-flow space being defined along the perimeter of the transport member and in communication with the reactor chamber. The reactor chamber comprises a wall defining a reaction zone, and the heating element is associated with the reaction zone, and adapted for heating reactants in the reaction zone. The cooling chamber has a wall defining a cooling zone that communicates with the reactor chamber. In one embodiment, the communication is through a cooling inlet, the diameter of the cooling zone being larger than the diameter of the cooling inlet. The temperatures of the reactant transport member, the reactor chamber, and the cooling chamber are independently controllable.

Abstract: A powder composition consisting essentially of an intimate mixture of boron carbide and titanium diboride, the mixture having an average particle size of less than about 0.5 micron, the particles being uniformly dispersed such that elemental analytical techniques show all discrete concentrations of boron carbide and titanium diboride to be less than or equal to about 0.5 micron in diameter, is disclosed. The powder is useful for making a densified ceramic composition comprising titanium diboride grains, having an average grain size of less than or equal to about 3 microns in diameter, uniformly dispersed with boron carbide grains, having an average grain size of less than about 5 microns in diameter. The densified composition exhibits improved hardness and toughness when compared wiht titanium diboride or boron carbide compositions.

Abstract: Carbides, nitrides or carbonitrides of elements from the main groups III and IV and sub-groups III, IV, V and VI of the periodic system of elements are prepared by(i) reacting compounds of the formula MX.sub.m or R.sub.n MX.sub.m-n with a reactive hydrocarbon-containing compound or a mixture of compounds which is polymerizable and which contains a reactive compound with one C--OH-group in whichM is an element of the main group III or IV or sub-group of III, IV, V or VI of the periodic system of elements,X is a halogen,R is hydrogen or alkyl or aryl,m is an integer corresponding to the valency stage of M,n is an integer from 1 to one less than the velency stage of M, and(ii) thermally decomposing the resulting product from (i) to the corresponding carbide or to the corresponding nitrides or carbonitrides with further nitridation.

Abstract: A process for forming carbides of silicon or metals in fine powder or whisker form. The process comprises forming a substantially uniform and non-agglomerated dispersion of a microfine powder of an oxide of silicon or a carbide-forming metal within a matrix of a polymer, carbonizing the oxide-containing polymer in an inert atmosphere and heating the carbonized product at high temperature to cause the oxide to react with carbon to form a carbide. The polymer must have a molecular weight of at least 10,000, a high carbon yield of at least 30% by weight, and a chemical structure which is infusible or capable of being rendered infusible. The preferred polymers are polyacrylonitrile, cellulose and polyvinyl alcohol, but other polymers with similar characteristics can be employed. The process is relatively inexpensive and gives an extremely finely divided product of high purity.

Abstract: Novel poly(alkenylpentaboranes) such as poly-2-vinylpentaborane are useful as precursors to BN or B.sub.4 C ceramics. The non-crosslinked poly(alkenylpentaboranes), which are soluble in common inert organic solvents, are prepared heat treatment of corresponding alkenylpentaboranes. The non-crosslinked poly(alkenylpentaboranes) are heated under an inert atmosphere to crosslink them, and the crosslinked products are pyrolyzed to yield B.sub.4 C. Alternatively, the non-crosslinked poly(alkenylpentaboranes) are heated in the presence of ammonia to yield a nitrogen-containing polymer which, upon pyrolysis, yields BN.

Abstract: There is disclosed a novel process and apparatus for continuously producing very fine, ultrapure ceramic powders from ceramic precursor reactants in a self-sustaining reaction system in the form of a stabilized flame thereof to form ceramic particles and wherein the thus formed ceramic particles are collected in the absence of oxygen.

Abstract: Boron-containing ceramics are formed from organoboron precermaic polymers which are carboralated acetylenic poolymers. The polymers can be formed by carboralating acetylenic or diacetylenic diols and condensing the diols to form carboralated polyesters. In an alternative process, polydiacetylene formed by the polymerization of diacetylene monomers having conjugated triple bonds are carboralated subsequent to polymerization. A process for obtaining readily soluble polydiacetylenes comprises heating a diacetylene diol in a high boiling solvent.

Abstract: Metal carbide and metal nitride powders produced by the carbothermal reduction of one or more metal oxides reacted with a binder material and a carbonaceous additive or optionally, a binder capable of supplying carbon to the reaction. The metal oxides are selected from among SiO.sub.2, Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2, HfO.sub.2 and B.sub.2 O.sub.3 and are combined with the binder in the presence of carbon to form granules having a controlled pore volume. The granules are then subjected to a carbothermal reduction reaction, in the presence of a nitrogen or a neutral atmosphere, to produce metal nitrides or metal carbides respectively, having an excess of carbon incorporated therein. The product is subsequently heated to react the excess carbon within the compound with oxygen from the atmosphere to form carbon monoxide gas, which may be removed by an optional exhaust system.

Abstract: A process for producing boron-containing ceramics such as boron carbide and boron nitride comprises pyrolyzing a blend of a precarbonaceous polymer such as polyacrylonitrile and a boron-containing polymer such as that formed by the reaction of a borane with a Lewis base. Pyrolyzation in an inert atmosphere yields boron carbide while pyrolyzation in a reactive gas burns away the precarbonaceous polymer and yiels a ceramic comprising the reaction product of boron and the pyrolyzation gas. Boron nitride ceramics are formed by pyrolyzing the preceramic blend in ammonia.

Abstract: Boron ceramics including boron ceramic fibers are formed by pyrolyzing at temperatures greater than 800.degree. C. organoboron polymers which have been formed by condensing decaborane with amines or phosphines.

Abstract: A method of producing submicron size boron carbide powder by heating a reactive mixture containing a boric oxide source and a carbon source at a high temperature for a sufficient length of time to form submicron particles of uniform size.

Abstract: A method of reprocessing neutron-irradiated contaminated boron carbide, including the steps of:dissolving the contaminated boron carbide in a mixture of sulfuric and nitric acids at an elevated temperature, to convert the boron carbide to boric acid, and to form an exhaust gas of nitric oxide and carbon dioxide;introducing water or tritiated, boric acid-containing water in liquid form under the surface of the hot acid mixture of the dissolving step, to produce steam;steam distilling the boric acid developed in the dissolving step with the aid of the steam generated in the introducing step, to separate the boric acid from nonvolatile radioactive and nonradioactive corrosion and irradiation products;condensing the boric acid-containing steam from the steam distilling s tep to yield boric acid and a condensate containing water or .sup.3 H-containing water;evaporating the condensate from the condensing step to dry and calcine the boric acid to form boron oxide and water vapor of .sup.

Abstract: Metal carbide and metal nitride powders produced by the carbothermal reduction of one or more metal oxides reacted with a binder material and a carbonaceous additive or optionally, a binder capable of supplying carbon to the reaction. The metal oxides are selected from among SiO.sub.2, Al.sub.2 O.sub.3, TiO.sub.2, ZrO.sub.2, HfO.sub.2 and B.sub.2 O.sub.3 and are combined with the binder in the presence of carbon to form granules having a controlled pore volume. The granules are then subjected to a carbothermal reduction reaction, in the presence of a nitrogen or a neutral atmosphere, to produce metal nitrides or metal carbides respectively, having an excess of carbon incorporated therein. The product is subsequently heated to react the excess carbon within the compound with oxygen from the atmosphere to form carbon monoxide gas, which may be removed by an optional exhaust system.

Abstract: A carbon-containing mixture is obtained by collecting a dispersed phase mixture from an aerosol which has been formed by introducing a decomposable carbon compound and a decomposable metallic compound into a hot gas containing steam.Since this carbon-containing mixture is extremely high in uniformity and consists of extremely fine particles, it can afford after heat treatment a metal carbide of high quality.

Abstract: A process for producing boron nitride which comprises providing a nitrogen-containing nitride promoter, preferably melamine or dicyandiamide, in contact with an admixture of boron oxide and a sufficient amount of boric acid to enhance the formation of boron nitride under a non-oxidizing atmosphere, and maintaining same at sufficiently elevated temperature to form boron nitride.

Abstract: A wear resistant multilayer coating is provided. The wear resistant coating comprises at least one internal layer and a thin, external layer of disordered boron and carbon applied to a substrate. The synergistic interaction of a hard internal layer and a lubricious boron and carbon layer provides a long lived tool coating. In a more specific embodiment, the external layer of the coating is disordered boron carbide. In accordance with one embodiment, the disordered boron and carbon external coating is of a composition B.sub.x C.sub.1-x where x is from about 0.60 to about 0.90.

Abstract: Cloth is coated at a temperature below about 1000.degree. C. with amorphous boron-carbon deposits in a process which provides a substantially uniform coating on all the filaments making up each yarn fiber bundle of the cloth. The coated cloths can be used in the as-deposited condition for example as wear surfaces where high hardness values are needed; or multiple layers of coated cloths can be hot-pressed to form billets useful for example in fusion reactor wall armor. Also provided is a method of controlling the atom ratio of B:C of boron-carbon deposits onto any of a variety of substrates, including cloths.

Abstract: A process for strengthening carbide fibers by removing internal stresses caused by their formation. This process is accomplished by drawing the carbide fiber under tension through a furnace. The temperature of the furnace may range from about 2050.degree. to 2300.degree. C. while the fiber tensile stress may vary from about 200 to 3500 p.s.i. when using boron carbide fibers with diameters ranging from about 8 to 14 microns.

Abstract: Processes of forming amorphous boron-carbon alloy in bulk form without crystallization are disclosed. Such products can be produced in thicknesses well in excess of ten mils by employing Reynolds number gas reactant flow conditions of 40 to 120. The resultant products of such processes having grain sizes preferably less than 30 A are also disclosed.

Abstract: A method of producing dense shaped articles of pure boron carbide that optionally contain 0.1 to 8% by weight of free carbon in the form of graphite is disclosed involving the steps of homogeneously mixing boron carbide in submicron powder form with small quantities of a carbon containing additive, forming the powder mixture into a shaped green body and then sintering the body in a controlled atmosphere and in the absence of external pressure at a temperature of about 2100.degree.-2200.degree. C. The shaped articles thus obtained are polycrystalline and, insofar as they correspond to the stoichiometric composition B.sub.4 C, single-phase; they have an average grain size of not more than 10 .mu.m, a density of at least 90% of the theoretical density of boron carbide and a flexural strength of at least 300 N/mm.sup.2. The fracture mode of the sintered articles is completely transcrystalline.

Abstract: Flexible metal carbide fabrics are produced by a process that involves the steps of:(a) impregnating a preformed organic polymeric fabric with a solution of a metal compound;(b) heating the impregnated fabric to evolve volatile decomposition products and to leave a carbonaceous relic containing the metal in finely dispersed form; and(c) further heating the relic to 1000.degree.-2400.degree. C. in a non-oxidizing atmosphere to form the metal carbide. Boron carbide and silicon carbide fabrics produced by this process are attractive for high temperature structural applications.

Abstract: A thin film of substantially defect-free pyrolytic graphite, useful as a bi-directional reinforcing material, is formed by vapor deposition on an inert liquid substrate surface and separated therefrom. The substrate temperature is substantially below the melting point of the refractory material and the substrate surface is smooth and free of stress to enable formation of a substantially defect-free film. Thin films of other refractory materials can be made similarly by first forming a pyrolytic graphite film on the substrate, and then vapor depositing a film of refractory material on the pyrolytic graphite surface. The pyrolytic graphite and refractory material films are then separated from the substrate surface and then separated from each other. Various refractory film materials can be made including pyrolytic grahite; boron; silicon; and refractory carbides, borides and nitrides. For making pyrolytic graphite films, it is preferable to use tin as the ubstrate, at a temperature of about 1600-1800.degree. C.

Abstract: This disclosure describes the process for producing an apparently amorphous porous boron carbide having a mean particle size less than 1 micron in diameter, effective pore sizes on the order of 30 Angstrom units, and surface areas on the order of 100 m.sup.2 /gr and greater. The process involves the gaseous phase reaction of acetylene (C.sub.2 H.sub.2) with diborane (B.sub.2 H.sub.6). The reaction is produced in a closed chamber initiated by an appropriate igniting device, such as a hot wire. This disclosure defines an optimum ratio of four parts diborane to one part acetylene and it describes the operating conditions under which the reaction occurs and the variation in physical properties and yield resulting from changes of ratio of the constituents. It also describes modification of the present batch process to a continuous production process.

Abstract: The preparation of metal and metalloid carbides, borides, nitrides silicides and sulfides by reaction in the vapor phase of the corresponding vaporous metal halide, e.g., metal chloride, with a source of carbon, boron, nitrogen, silicon or sulfur respectively in a reactor is described. Reactants can be introduced into the reactor through a reactant inlet nozzle assembly. Inhibition and often substantial elimination of product growth on exposed surfaces of such assembly is accomplished by introducing the corresponding substantially anhydrous hydrogen halide, e.g., hydrogen chloride, into the principal reactant mixing zone.

Abstract: A process for strengthening carbide fibers by removing internal stresses caused by their formation. This process is accomplished by drawing the carbide fiber under tension through a furnace. The temperature of the furnace may range from about 2050.degree. to 2300.degree.C while the fiber tensile stress may vary from about 200 to 3500 p.s.i. when using boron carbide fibers with diameters ranging from about 8 to 14 microns.